Hi guys. In need of some help before the car goes into the garage. I have a 57 reg 520d lci that has just developed a problem. Cars been fine until now. Has done 80,000 miles and looked after pretty well. Came off the motorway earlier and heard a really loud whining noise followed by a loss in power. The whine sounds really high pitch and not whistle like, more like a cat stuck under the bonnet. It makes the noise when revved standing still and when driven too, the noise gets louder higher up the rev range. No smoking at all and no oil burning either.

If so the impeller assembly is moving inside the casing, sooner or later the blades will touch the metal casing and possibly shatter, maybe even breaking the seals in which case they could make it into the engine causing further damage and you would see smoke and oil makes it where it shouldn't be.

You may find a little black smoke if you have continued to drive it.

Alternatively if it is a split hose you may hear a high pitched whistling possibly

First sorry for reviving an old thread.
Did a new turbo fix your problem?
This happened to me today. I tried accelerating while going up hill en the power just dissapeared, turned down the radio and yeah it does sound like a cat in pain. Towed my car back home and started ripping it appart, there is alot of play in the impeller, but it is not damaged so the engine should be fine. My car has rolled 159 000km (about 100k miles) and I haven't noticed any thing until yesterday when I had a sudden abrupt powerloss when accelerating hard, but it was fine again so I blamed the DTC for it. My car has been slightly hesitant around 1500-2000RPMs, but nothing out of the ordinary for a turbo diesel. Will replace it my self with a core exchange as BMW want £2000 for a new turbo and at least £2000 for the work. Will clean an check my inlet manifold and all hose while I'm waiting for my overhauld turbo. BTW my car is a December 2005 build E91 320D